Welcome to the Radon Project at Columbia University. This website was created by Prof. Andrew Gelman at
Columbia University and Dr. Phillip N. Price at the Lawrence Berkeley National Laboratory
to assist U.S. homeowners in deciding what to do about radon (if anything).

Radon is a radioactive gas that can enter your house from the ground. It decays radioactively into other radioactive elements that can cause lung cancer.
You might want to
measure your house for radon and possibly reduce the level of radon in your house through
remediation. Here's some
More on radon and why we care about it.

Based on the information you provide, this website will estimate the radon level in your house and how much risk of lung cancer this will cause,
and will provide a recommendation as to whether you should:

take a year-long radon
measurement (and then use that information to decide
whether to remediate), or

take a short-term radon measurement (and then use that information to decide whether to
remediate), or

do nothing. (If we recommend "do nothing", that doesn't guarantee that you don't have a radon problem, it just means that you probably don't have a problem. If you want to be sure, go ahead
and make a measurement!)

The map below shows median living-area radon levels (half the homes are higher, half lower) for counties in
the contiguous United
States. Areas in grey mostly have low radon levels; redder
areas have higher levels. But there is a lot of local variation, and
high-radon houses and low-radon houses exist in all areas of the U.S.